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grin007 [14]
4 years ago
9

If you install special sound-reflecting windows that reduce the sound intensity level by 33.0 dBdB , by what factor have you red

uced the sound intensity
Engineering
1 answer:
Sever21 [200]4 years ago
3 0

Answer:

The sound intensity is reduced by a factor of 1995.26

Explanation:

When comparing two sound intensities, the intensity level is measured in the unit of decibel or dB. The intensity of the threshold of hearing for a human being is  10^−12 W/m^2 . When the intensity level is zero, it means that the sound intensity is the same as the threshold of hearing.

The reduced sound intensity level is given as 33 dB, so

10  log (I/Io)  = - 33

I  : intensity of the sound

Io ( =   10^−12 W/m^2): threshold of hearing

So, the intensity ratio is

I/Io = 10^-3.3

     = 5.01 x 10^-4

1/ 5.01 x 10^-4 = 1995.26

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A rigid tank contains an ideal gas at 40°C that is being stirred by a paddle wheel. The paddle wheel does 240 kJ of work on the
Sergeu [11.5K]

To solve the problem it is necessary to consider the concepts and formulas related to the change of ideal gas entropy.

By definition the entropy change would be defined as

\Delta S = C_p ln(\frac{T_2}{T_1})-Rln(\frac{P_2}{P_1})

Using the Boyle equation we have

\Delta S = C_p ln(\frac{T_2}{T_1})-Rln(\frac{v_1T_2}{v_2T_1})

Where,

C_p = Specific heat at constant pressure

T_1= Initial temperature of gas

T_2= Final temprature of gas

R = Universal gas constant

v_1= Initial specific Volume of gas

v_2= Final specific volume of gas

According to the statement, it is an isothermal process and the tank is therefore rigid

T_1 = T_2, v_2=v_1

The equation would turn out as

\Delta S = C_p ln1-ln1

<em>Therefore the entropy change of the ideal gas is 0</em>

Into the surroundings we have that

\Delta S = \frac{Q}{T}

Where,

Q = Heat Exchange

T = Temperature in the surrounding

Replacing with our values we have that

\Delta S = \frac{230kJ}{(30+273)K}

\Delta S = 0.76 kJ/K

<em>Therefore the increase of entropy into the surroundings is 0.76kJ/K</em>

8 0
3 years ago
Convenience items like liquid egg are a lot more expensive?<br> True<br> Or False
Alchen [17]
It’s true because convenience stores are more expensive so that means overall the items would be more expensive.
3 0
3 years ago
Read 2 more answers
WHAT IS A VACUOMETER?
Alex_Xolod [135]
It is a tool used to measure Low pressure
4 0
3 years ago
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Discuss the chemical and physical properties of crude oil​
mr Goodwill [35]

Answer:

Denser and more viscous crude oils have greater concentrations of other components, including resins and asphaltenes, which contain more polar compounds, often including “heteroatoms” of nitrogen, sulfur, and oxygen as well as carbon and hydrogen.

7 0
4 years ago
Using the tables for water determine the specified property data at the indicated state. For H2O at T = 140 °C and v = 0.2 m3/kg
Dennis_Churaev [7]

Answer:

h = 1429.74\,\frac{kJ}{kg}

Explanation:

The determination of any further properties requires the knowledge of two independent properties. (Temperature and specific volume in this case). The specific volumes for saturated liquid and vapor at 140 °C are, respectively:

\nu_{f} = 0.001080\,\frac{m^{3}}{kg}

\nu_{g} = 0.50850\,\frac{m^{3}}{kg}

Since \nu_{f} < \nu < \nu_{g}, it is a liquid-vapor mixture. The quality of the mixture is:

x = \frac{\nu-\nu_{f}}{\nu_{g}-\nu_{f}}

x = \frac{0.2\,\frac{m^{3}}{kg} - 0.001080\,\frac{m^{3}}{kg} }{0.50850\,\frac{m^{3}}{kg} - 0.001080\,\frac{m^{3}}{kg} }

x = 0.392

The specific enthalpies for saturated liquid and vapor at 140 °C are, respectively:

h_{f} = 589.16\,\frac{kJ}{kg}

h_{g} = 2733.5\,\frac{kJ}{kg}

The specific enthalpy is:

h = h_{f}+x\cdot (h_{g}-h_{f})

h = 589.16\,\frac{kJ}{kg}+0.392\cdot \left( 2733.5\,\frac{kJ}{kg} - 589.16\,\frac{kJ}{kg} \right)

h = 1429.74\,\frac{kJ}{kg}

6 0
4 years ago
Read 2 more answers
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